(1) Field of the Invention
This invention relates in general to the production of thermally processed, shelf-stable egg products which are texturally acceptable.
(2) Description of the Prior Art
Heretofore, there has not been a thermally processed, shelf-stable, egg product which has retained satisfactory textural quality. There are several problems associated with subjecting eggs to the high heat necessary to sterilize in order to produce a shelf-stable product which are not encountered when one cooks eggs for immediate consumption. The most serious difficulty is that a heat process sufficient to sterilize will cause the egg product to become rubbery and to harden undesirably. Syneresis or weeping is also encountered with prolonged heating. A third difficulty is that the sulphur in the egg white reacts with the iron in the egg yolk to produce ferric sulfide, causing the eggs to develop a green color. Further, scrambled egg products tend to solidify into one solid mass during the sterilization process in the absence of a means to prevent solidification.
The problem of syneresis has been encountered in the production of frozen egg products as well as in cooked egg products. In U.S. Pat. No. 3,565,638, it was recognized that scrambled eggs prepared from thawed frozen whole eggs would "weep" due to syneresis when kept at serving temperature on a hot plate. It is known that syneresis results when the three-dimensional egg albumen gel structure formed upon application of heat, retrogrades to a more orderly, partially crystalline, state. Milk solids and edible starches have been used to decrease syneresis. Vegetable gum has also been used to increase the viscosity of the egg mixture. The production of green color has been prevented by use of disodium or calcium disodium ethylenediamine-tetraacetate (EDTA) and by acidification of egg compositions with an edible acid or acid salt to a pH below 7.1. Another method of improving the color of cooked egg products is disclosed in U.S. Pat. No. 3,598,612. In that invention, the egg yolks and whites are separated, the yolks treated with an edible oxidizing agent and then the yolk is surrounded by egg white and further processed.